ML20116E849
| ML20116E849 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/02/1992 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20116E846 | List: |
| References | |
| NUDOCS 9211100049 | |
| Download: ML20116E849 (12) | |
Text
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ATTAC104ENT B Proposed changes to Appendix A Tochtical Specifications of Facility Operating License NPF-18.
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DP 921110o049 DR 921102 l p ADOCK 05000374 PDR
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g TABLE 3.6.3-1 (Continued)
PRIMARY CONTAll8ENT ISOLATION VALVL pi VALVE FINICTION AGS IReeER e
g d. Other Isolatten Valves ,
5 1. si, m. C.st,,, ,, -
2E32-Fat 1A.'E. J. NI *I Inserp n 2. Reactor Feeduster and EtU System Return 2821-F91eA, 3 ^
2821-F06 8 Tnsert ,,
2G33-F For the remainder of Cycle 5, or until
[
the first outage in which the unit is in g
- 3. EeSIduel lleet Bemoval/Lew Pre 65#re Coelent Injectfen System cold shutdown for two weeks or greater )
$ 2E17-'942A, 5. C .
durati n, the Type C test is not !
2E1 M U64, E required to be current for the 2G33-F040 gg}g.,ggy4 g
, valve and its.2eakage is not required to 2E12-FM, a UI b* includ'd in th* t tal TYPE B E. C 2E12-FS27A,8fg )
leakage specified by specification 2E12-F924 3.6.1.2.b. .
2E12-F064A, 80g UI 2E12-FS11A, 3 I 2E12-F0004, 8. C 5
2E12-F025gII,C 2E12-F830 2E12-F805UI 2E12-F0734, B Idl 2E12-F0744, BI I 2E12-F0554. BUI
~ 2E12-F036A SUI
- f. 2E12-F311A, BUI III g 2E12-F941A, Sggj .
2E12-F05eA, 8 e,
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o hTTACID4ENT C i
!h Evaluation of Significant Hazards Consideration W
- &v 9 ; mtsuwealth Edison 1 a evaluated the 1,roposed Technical Specification Ame ru'rie n t and determined th a t, it does not repre int a signiffcant hazards c c,n s i de r a t i on . 13ased on the criterla for def 4 g a sign; . cant hazards causidecation established in 10 CFK 50.92, operat on of LaSalle County Station i
'g g 'n 2 in accordann . tith the propoced amendment will nots t
I '"r a significant incrense in the probability or consequences of an
.. nt previc.usly evaluated becaucc O
'b the probabl31ty or an accident previously evaluated 18 not increased, JT ao the accident initiators for the Feedwater or Reactor Water f'Ir nup JCU ) return lino breaks discussed in the UFSAR are nd t.! f ected by N ,tlal leakage through the 2G33-F040. The consequ;nces of an eccident g ; ously evaluated is not significantly increased, because the Feedwater il 1smation check nu vo s form a leakage barrier and are the boundary g / for the Coatainment Integrat$d Lenk Rate rest (Type A tost). Also, the g- RWCU return line forms a te sted leakage barrier for long term leaka9 control.
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- 2. Create the possibility of a new or diiferent kind of accident from any '
accident previously evaluated be- se y p
The use of the 2G33-F040 t long 'c on l' 3 jon boundary following a RWC.I return line break was pret ionaly evalu.R the nonconservative Type C ter a does not create a new or o,1forent accident, becruse the. RWCU 2- to ms the long term isolation boundary utilizing both the e 1-F040 ant me 2GJJ-F039 check valve.
- 3. Involve a s'7nificant reduction in the margin c.1 Falety because:
TNe combined leakage of the 2G33-F040 and the 2G33-F039 chec t valve are within allowable limite for tlw Reactor Water Cleanup return line.
? The feedwster isolation check valve leakages are witt.in limits for the feedwater lines and fulfill the automatic isolation function for the feedwater containment penetrations. Therefore, there is no significant
% reduction in the margin of safety.
- 'iu l dance has been provided in " Final Procedures and Standt' .is on No
' Ahj,4 Significant Hazards Considerations," Final Rule, application of standards to license change requests for determin'.cion of the 51 FR 774 , for the g existence of s ig n i f icar'- harards considerations. This document provides examples er amendments which ace and are not considered lilely to involve significant hazards considerations. The ptoposed Technical Spe :ification
- w. ch.nge to Technical Specification 3.6.3, for the Recctor Water Cleanup Return to feedwater Valve, t.ost closely fits the example of a change which may either result in some incraare to the probability or consequences of a previously analyzed accident or c.ny reduce in some way a safety margin, but where the results cf the change are cleacly within all acceptable criteria with respect
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'to 'the system or' component specified in the Standard. Review: Plan and-exceptions as approveC in.NUREG 0519, Safety _ Evaluation Report Related j y the Operation of LaSa110. County Station Units 1 and 2, Merch,-1981. The Feedwater isolation check valves form the automatic isolation boundary for the feedwater'_
and reactor water cleanup lines and were 'satisf actorily-- leak . rate tested-during the last refael outage on Unit 2. The Reactor Water Cleanup Return to-Feedwater Valve, 2G33-F040, in . conjunction Ith the _ upstream check valve 2G33-F039 form a satisfactory leak tested line even though the . 2G33-F040 leskaga can not be proven to be a specific - value based on the Type C - teLt method used during the last Urlt 2 refuel outage.
- ihe proposed Technical Specification amendment does not involve a significant-relaxation of the criteria used to establish safety _ limits, a significant-relaxation of the bases for the limiting safety system settings or ta significant relaxation of the bases for the . limiting conditions for operations. Therefore, based on the guidance provided- in the Federal Register and the criteria established in 10 CFR 50.92(c), the _ proposed change does *'t constitute a significant hazards consideration.
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- L ATTACIMENT D l
l Environinental Assessment Statement Applicability Review -
The Feedwater loolntion check valvas form the automatic isolation of the feedwater lines and were satisfactorily leak rete tested during the last refuel outage on Unit 2. The Reactor Water Cleant.p Return te feedwater Valve, 2G33-F0(0, in conjunction witn the upstream check valve 2G33-F039 'orm a satisfactory leak testeC line even though the 2G33-F040 leakage can not ; be -
proven to be a specific value based on the Type C test method used daring the last Unit 2 refuel outage. Therefl.e, the possitity of leakage to the environment via a Reactor Weter Cleenup re "rn line b, '
-t remains uncharried.
The , oposed amendment does not involve a' change in the installation or use of t '.4e facilities or components located within the restricte; areas a r.
defined in 10 CFR 20. Commonwealth Edison has determined that this proposed amendment does not involve -a significant increase in the amount, or a significant change in the typer, of any effluents that may be' released off-site and that there is no significant increase in individual or cumulative occupational radiation exposure. This dete rmination . was based on the limited time frame for continued operation associated with the nonconservative Type C.
test method for the Reactor Water Cleanup Return to. Feedwater Valve, 133-F040, and the mitigating feature of the combined leakage test of the
.G33-F040 in conjunction with the upstream- check valve 2G33-F039.
Accordingly, this proposed amendment meets the_ eligibility criteria lfor categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to - 10 CFR 51.22(b), ac environmental impact statement or . environmental- assessment need be prepared in connection with granting o r the proposed amendment. ,
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.'l ATTACID4ENT E
- Additional Support Material-A. Appropriate pages of LaSalle UFSAR.
B. Figure 1, Simplified drawing of the Feectwater' and RWCU piping.
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LSCS-UPSAR e
6.2.4 containnnnt Isolation Syston The primary' objective of the containment isolation system isLto provide protection against the release of radioactive materials to the environment through the fluid system lines penetrating the containment. This objective is accomplished by ensuring that isolation barriers are provided in all fluid lines that penetrate primary containment, and that automatic closure of the appropriate isolation valves occurs.
6.2.4.1 Desian Bases The design requirements for containment isolation barriers are:
- a. The capability of closure or isolation of pipes or ducts that penetrate the containment is provided to ensure a containment barrier sufficient to maintain leakage within permissible limits.
- b. The arrangements of isolation valving and the criteria used to establish the isolation provisions conform to the requirements of General Design Criteria 54 through 57, as discussed in Section 3.1.
- c. The design of all containment isolation valves and associated piping at4 penetrations is Seismic Category I.
- d. Containment isolation valves and associated piping and penetrations meet the requirements of the ASME Boiler and Pressure Vessel Code,Section III, for Class 1 or 2 components, as applicable.
- e. Isolation values, actuators, and controls are protected against loss of eafety function from missiles and accident environments.
- f. Containment is'!ation valves provide-the necessary isolation of u containment in the event of' accidents or other conditions to-limit the untreated release of radioaud ve materials f rom the containment in excess of the design limits.
- g. Appropriate isolation valves are automatically closed by the signals listed in Table 6.2-21. The criteria-for assi.gt.ing isolation signals to their associated isolation valves is described in Subsection 7.3.2. l Once the isolation function iF initiated, it goes to completion.
- h. Redundancy and physical separacion are required in the electrical and mechanical design to ensure that no single failure in the svstem prevents the system from performing its safety function.
6.2-48 REV. 1 - APRIL 1985
LSCS.UPSAR The governing conditions under which containment isolation becomes mandatory are high drywell pressure or low water level in the reactor vessel. One jr both of these signals initiate clo tre of isolation valves not required for emergency shutdown of the plant. These same signals also initiate the ECCS. The valves associated with ra ECCS may be closed remote manually from the control room or clone automatically, as appropriate.
Excess flow check valves are used ac a means of automatic isolation on all static instrument sensing lines that penetrate the drywell containment and connect to either the reactor pressure boundary or the drywell atmosphere. The valve is located downstream of the root valve and as close as practical to the outside surface of the containment. This valve is automatically closed to restrict flow in case of a sensing line break outside containment.
Dead-end instrument sensing lines that are in communication with the reactor pressure boundary and penetrate the primary containment are equipped with 1/4 inch orifice as close to the process as possible inside the drywell.
6.2.4.2 System Desion, Table 6..-21 presents the design information regarding the containment isolation provisions for fluid system lines and instrument lines penetrating the containment. Containment isolation signals are ider.tified in Table 6.2-21 and valve arrangements are represented in Figure 6.2-31.
The plant protection system signals that initiate closure of the containment isolation valves are listed in Teble 7.3-4. l The isolation provisions follow the requirements of General Design Criteria 54, 55, 56, and 57 as described below. The justification for this design is also presented.
6.2.4.2.1 Eyaluation Against General Design Criterion 55 l Feedwater Line Each feedwater line forming a part of the reactor coolant ,i pressure boundary is provided with a nonslam type check valve ,
inside the containment, and a nonslam type, air operated testable !
check valve outside the contair. cent, as close as practicable'to l the containment wall. In addition, a motor-operated gate valve is i.ustalled upstream of the outside isolation valve to provide i long-tarm isolation capability, i l
During a postulated LOCA, it is desirable to maintain reactor l coolant makeup from all available sources. Therefore, it would not improve safety to install a feedwater isolation valve-that closed automatically on signals indicating a LOCA, and, thereby, eliminate a source of reactor makeup. The provision of the check 1
6.2-49 REV. 1 - APRIL 1985 l l
LSCS-UFSAR valves, however, ensure the prevention of a significant loss of reactor coolant inventory and offer immediate isolation shoald a break occur in the feedwater line. For this reason, the outermost valve does not automatically isolate upon signal from tne protection system. The valve is remote manually closed from the main control room to provide long-tern leakage protection upon operator determination that continued makeup from the feedwater system is unavailable or unnecessary.
In addition, the outboard check valve is provided with a special actuator that performs the following functions:
- a. The actuator is capable of partially moving the valve disc into the flow stream during normal plant operation in order to ensure that the valve is not bound in the open position. The actuator is not capable of fully closing the valve against flow, however, and there is no significant disruption of feedwater flow.
- b. The actuator is capable of applying a seating force to the valve at low differential pressures'and abnormal conditions. This improves the leaktightness capability of the valves. The actuator vill be utilized during leak testing.
ECCS Lines to the,,sFV The HpCS, LPCS, and LpCI lines penetrate the dryvell and inject coolant directly into the reactor pressure vessel. Isolation is provided on each of these lines by a normally closed air testable check valve inside the containment and a normally closed motor-operated gate valve located outside the containment, as close as practicable to the exterior wall of the containment. If a loss-of-coolant accident occurred, each of these valves would be re s ulted to open to supply coolant to the RPV, The motor-operated gate valves are automatically opened by their appropriate signals, and the check valves are opened by the coolant flow in the line. The opening capability of the check valve can be tested from the main control room during cold shutdowns by exercising the valve disk open-close with the special actuator provided fo- this purpose. -position indic& ting lights are provided in the ce :rol room to monitor the valve disk position.
Control Dod Drive Lines The control rod drive system, has two types.of lines to the RPV; the in:ert and withdraw lines that penetrate the drywell and cont.ect to the control rod drive.
The control rod drive insert and withdraw lines can be isolated by the solenoid valves outside the primary containment. These lines that extend outside the primary containment are small, and 6.2-50 REV. 0 - APRIL 1984
LSCS-UTSAR r' termina'oe in a system that is designed to prevent out-leakage.
Solenoid valves normally are closed, but open on rod movement and during reactor scram. In addition, a ball check valve located in the control rod drive flange housing automatically seals the insert line in the event of a break.
RBR :s ad RCIC Head Spray Lines .
The RBR and RCIC het i spray lines meet outside the containment to form a common line vnich penetrates the drywell and discharges directly into the reactor pressure vessel. The testat:e check valve inside the dryvell is normally closed and nas position indication lights in the main control room to verify its position. The testable check valva is located as close as practicable to the reactor pressure vessel. Two types of' valves, a testable check valve and a normally closed actor-operated remote manual gate valve, are located outside the containment.
The check valve assures immediate isolation of the containment in the event of a line break. The globe valve on the RHR line receives an automatic isolation signal while the gate valve on the RCIC line is remote manually actuated to provide long-tern leakage control. .
Standby Liquid Control Systes Lines The standby liquid control system line penetrates the drywell and connects to the reactor pressure vessel. In addition to a simple check valve inside the drywell, a check valve together with an explosive actuated valve are located outside the drywell. Since the standby liquid control line is a normally closed, nonflowing line, rupture of this line is extremely remote. The explosive actuated valve, though, functions as a third isolation valve.
This valve provides an absolute seal for long-tern leakage control as well as preventing leakage of sodium pentaborate into the reactor pressure vessel during normal reactor operation.
Reactor Water Cleanup System The reactor water cleanup (RWCU) pumps, heat exchangers, and filter derineralizers are located outside the primary containment. The return line from the filter demineralizers connects to the feedwater line outside the containment between the outside containment feedwater eneck valve and the outboard motor-operated gate valve. Isolation af this line is provided by the feedwater system check valve inside the containment, the feedwater check valve outside the containment, anI a motor-operated gate valve which provides a long term ic:;1ation capability.
During the postulated loss-of-coolant accident, it.is desirable to maintain reactor coolant takeup. For this reason, valves which automatically isolate upon signal are not included in the design of the system. Consequently, a third va /e is required to provide long-term leakage control. Should a break occur in the 6.2-51 REV. 0 - APRIL 1984
LSCS-DFSAR
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reactor water cleanup return line, the check valves would prevent significant loss of inventory and offer immediate isolation, while the outermost '. solation valve would provide long-term
_ leakage' control.
Recirculation pbsp Seal Water Supply Line The recirculation purp seal water line extends from the recirculation pump through the dryvell and connects to the CRD supply line outside the primary containment. The seal water line forms a part of the reactor coolant pressure boundary, therefore the consequences of failing this line have been evaluated. This evaluation shows that the consequences of breaking this line is less severe than that of failing an instrument line. The recirculation pump seal water line is 3/4-inch Class B from the recirculation pump through the second check valve (located outside the containment). From this valve to the CRD connecticn the line is Class D. Should this line be postulated to fail and either one of the check valves is assumed not to close (single.
active failure), the flow rate through the broken line has been calculated to be substantially less than that permitted for a broken instrument line. Therefore, the two check valves in series provide sufficient isolation capability for postulated failure of this line.
RER Shutdown Cooling Return Line The shutdown cooling return lines are ccnnected to the reaccor recirculation pump discharge lines. Tle isolation valve arrangement on these lines is identical to that on the ECCS lines connected to the RPV. However, the motor-operated valve outside containment closes automatically upon receipt of an isolation signal.
6.2.4.2.2 Evaluation Against General Desion Criterion 56 RCIC Turbine Exhaust Vacuum Breaker Line Minimum Flow Bypass The RCIC turbine exhaust line is provided with a vacuum breaker system to prevent condensation of the-exhaust steam from inducing a vacuum in the line. The vacuum relief line connects the turbine exhaust line to the suppression chamber atmosphere. Tvc check valves in-series in the line prevent steam from exhausting to the vapor space above the pool, and two motor-operated globe valves, one on either side of the-aforementioned check valves, provide remote manual isolation capability for the RCIC turbine exhaust race:m breaker line.
6.2-52 REV. 0 - APRIL 1984
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